Technical Field
The present disclosure relates to an image forming apparatus, an image forming method, and a non-transitory recording medium storing an image forming program.
Description of the Related Art
Conventionally, an electrophotographic image forming apparatus performs a charging process in which the surface of a photoconductor is uniformly charged. Typically, a direct-current (DC) contact charging method is employed as the charging process. In the DC contact charging method, a charging roller applied a DC voltage contacts the surface of the photoconductor, and discharge between the charging roller and the surface of the photoconductor occurs and charges the surface of the photoconductor to a target electric potential.
In the DC contact charging method, the charging roller contacts the surface of the photoconductor. Accordingly, as the photoconductor rotates, the charging roller scrapes a photoconductor film on the surface of the photoconductor. Over time, as the photoconductor film becomes thinner, the relation between the voltage applied to the charging roller and the surface potential of the photoconductor changes, and the surface potential of the photoconductor required for proper image formation cannot be maintained and it becomes necessary to replace the photoconductor.
Additionally, if the photoconductor film is entirely scraped off, charging performance sharply deteriorates because holding a charge on the surface of the photoconductor becomes impossible. Therefore, it is necessary to replace the photoconductor.
To counter these problems, a conventional image forming apparatus uses rotations of a photoconductor to calculate a scraping amount of the thickness of a photoconductor film of the photoconductor, which is also referred to as the film thickness of the photoconductor, and controls the voltage applied to a charging roller or determines the life of the photoconductor. But the film thickness of the photoconductor estimated by using rotations of the charged photoconductor may greatly differ from the actual film thickness of the photoconductor depending on (1) usage environment, (2) pressure of a blade that abuts the photoconductor in a photoconductor unit, and (3) nip pressure in a developing unit.